1. Field
One or more aspects of embodiments according to the present invention relate to receivers, and more particularly to a system for processing signals from a receiving array antenna.
2. Description of Related Art
Array antennas may be used to receive signals with a directional receive beam by suitably combining the signals from antenna elements of the array antenna. Some related art techniques involve applying a phase shift or time delay to the signal from each antenna element, the phase shift or time delay corresponding to the phase shift of an expected signal from antenna element to element in the direction of the receive beam. If the signals are first converted to digital form, the process of time delay may employ interpolation to estimate signal amplitude at a time other than the actual sampling times, which may be computationally costly and which may introduce numerical errors (the estimate of amplitude may be imprecise). Moreover, a sampling frequency at least equal to the Nyquist frequency may be required in some cases, to avoid replication of signals in unexpected frequency bands (e.g. aliasing); if the Nyquist frequency is relatively high, sampling at this rate may be challenging or costly. The Nyquist frequency may be twice the highest frequency of the sampled frequency band or if the signal is analog bandpass sampled the Nyquist frequency may be closer to twice the bandwidth of the sampled frequency band. Thus, there is a need for a flexible system for processing signals from a receiving array antenna that is compatible with sampling at frequencies lower than the Nyquist frequency.